small molecule drug discovery

Decades of Discovery: How the NCI-60 Revolutionized Cancer Drug Screening

Posted on by Kendra Hanslik

The National Cancer Institute’s NCI-60 drug screening panel, comprised of 60 diverse human cancer cell lines, has been a cornerstone in advancing cancer research and drug discovery since its inception in the late 1980s. Developed in response to the need for more predictive and comprehensive preclinical models, the NCI-60 facilitates the screening of thousands of compounds annually, aiming to identify potential anti-cancer drugs across a broad spectrum of human cancers. This article traces the origins, development, and evolution of the NCI-60 panel, highlighting its significant role in advancing our understanding of cancer and therapeutic agents.  

Continue reading “Decades of Discovery: How the NCI-60 Revolutionized Cancer Drug Screening”

From Hit to Live-Cell Target Engagement Assay: DNA-Encoded Library Screens and NanoBRET™ Dye

Posted on by Tian Yang

Monitoring and quantifying drug-target binding in a live-cell setting is important to bridging the gap between in vitro assay results and the phenotypic outcome, and therefore represents a crucial step in target validation and drug development (1). The NanoBRET™ Target Engagement (TE) assay is a biophysical technique that enables quantitative assessment of small molecule-target protein binding in live cells. This live-cell target engagement assay uses the bioluminescence resonance energy transfer (BRET) from a NanoLuc® luciferase-tagged target protein and a cell-permeable fluorescent tracer that reversibly binds the target protein of interest. In the presence of unlabeled test compound that engages the target protein, the tracer is displaced, and a loss of BRET signal is observed. Due to the tight distance constraints for BRET, the signal measured is specific to the target fused to NanoLuc® luciferase.

Live-cell target engagement assay using NanoBRET to measure small molecule binding to a target transmembrane protein.

Promega offers over 400 ready-to-use assays for multiple target classes, including kinases, E3 ligases, RAS, and many others. For targets that do not have an existing NanoBRET™ TE assay, Promega offers NanoBRET™ dyes, NanoLuc® cloning vectors, and NanoBRET™ detection reagents to develop novel NanoBRET™ TE assays.

To learn more about the NanoBRET™ TE platform, see the NanoBRET™ Target Engagement Technology Page on our website.

One critical component in the development of novel NanoBRET™ TE assay is the creation of the cell-permeable fluorescent tracers (NanoBRET™ tracers) against the target protein of interest. The tracers are bifunctional, consisting of a NanoBRET™-compatible fluorophore and a target-binding moiety connected by a linker. While the NanoBRET™ 590 dyes have demonstrated consistently robust cell permeability and optimal spectral overlap with NanoLuc® for BRET, a ligand capable of binding to the target protein of interest needs to be identified to generate a NanoBRET™ tracer.

What Are DNA-Encoded Libraries?

DNA-Encoded Libraries, (DELs), have emerged as powerful tools for discovering small molecule ligands to target proteins of interest at an unprecedented scale. . owing to the ability of a DEL  to enable the synthesis of larger libraries of compounds and to target proteins without any prior structural knowledge of the proteins or their ligands (2). Because each member of a DEL contains a DNA barcode and a small molecule separated by a linker, DEL is primed for discovering leads within therapeutic modalities that rely on bifunctional chemistry, such as proteolysis targeting chimeras (PROTACs). Since NanoBRET™ tracers are also bifunctional, ligands identified from DEL selections could serve as ideal candidates for developing novel NanoBRET™ tracers that can enable NanoBRET™ TE assays for new targets.

Continue reading “From Hit to Live-Cell Target Engagement Assay: DNA-Encoded Library Screens and NanoBRET™ Dye”

Small Molecule Therapies and Immunotherapies: An Introduction to Targeted Cancer Treatments

Posted on by Kelly Grooms

Cancer is a deceptively singular term for hundreds of different diseases. These diseases can affect almost any part of the body.  In the United States, cancer is the second most common cause of death (1). At its most basic level, however, cancer is the abnormal and uncontrolled division of cells resulting from genetic changes in one or more cells.

This prolific cell division is what many standard chemotherapies act upon. These therapies are developed to kill rapidly dividing cells but often don’t discriminate between normal and cancerous cells. In contrast, targeted therapies are designed to interact with (or target) specific pathways, processes or proteins whose abnormal behavior is associated with cancer development and growth. Targeting these abnormal cellular functions can counteract cancer in different ways. They can interfere with tumor growth, carry other drugs into tumor cells or help the immune system find and kill cancerous cells. Targeted therapies can be loosely divided into two categories: small molecule therapies and immunotherapies.

Continue reading “Small Molecule Therapies and Immunotherapies: An Introduction to Targeted Cancer Treatments”